1. Field of the Invention
The invention is related to a polishing technique, and more particularly to a polishing pad, a polishing system and a polishing method capable of enabling a slurry to have a different flow distribution.
2. Description of Related Art
With the progress of the industries, planarization processes are often adopted as processes for manufacturing various devices. Chemical mechanical polishing (CMP) processes are often used in the planarization processes in the industries. General speaking, the chemical mechanical polishing processes are performed by supplying a slurry which has chemical mixtures on a polishing pad, applying a pressure on the article to be polished to press it on the polishing pad, and providing a relative motion between the article and the polishing pad. Through the mechanical friction generated by the relative motion and the chemical effects of the slurry, a portion of the surface layer of the article is removed to make the surface flat and smooth so as to achieve planarization.
FIG. 1 is a schematic top view of a conventional polishing pad, and FIG. 1A is a cross-sectional view of the polishing pad taken along a line A-A′ in FIG. 1. Referring to FIG. 1, a polishing pad 100 includes a polishing layer 102 and a plurality of circumferential grooves 104. The plurality of circumferential grooves 104 are disposed in a concentric arrangement in the polishing layer 102 to contain the slurry. When the polishing process is performed, the polishing layer 102 contacts a surface of an article 105 (e.g. a wafer), and the polishing pad 100 rotates along a rotational direction 101 simultaneously. At the same time when the polishing pad 100 is rotating, the slurry is continuously supplied to the polishing pad 100 and flows between the polishing layer 102 and the article 105.
Referring to FIG. 1A, due to the centrifugal force generated from the rotation of the polishing pad 100, a part of the slurry flows outward in a radial direction from the circumferential grooves 104 to the surface of the polishing layer 102, as shown by a flowing direction 103. During the polishing process, a flow distribution of the slurry affects polishing characteristics. Therefore, it is necessary to provide polishing pads which have different flow distributions for industry in response to the requirements of various polishing processes.